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Member Posts: 3
We live on the 5th floor in a Co Op building in Brooklyn. Lately the radiator goes on at 6 AM and we start to hear banging between the floorboards until 6:20 AM when the radiator turns off. This is the only time we hear this water hammering sound, the 20 mins the radiator turns on first thing in the morning. Its loud enough to wake us up in the morning. We don't hear the noise during the day. We have a baseboard-style radiator.

Our super came and all he did was change the air valve in our radiator, but the water hammering noise still occurred the next morning.

Can the problem be that the water level is set too high? Is there water built up in places were it shouldn't be? We really just want a morning on uninterrupted sleep. Any thoughts/solutions would be greatly appreciated.

• Member Posts: 4,106
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Pipes can lose their pitch in older buildings. Pipe hangers break, buildings settle, piping re-worked and not done properly.......causing water to remain in the pipes after the heat is turned off. When the boiler starts making steam again and the steam starts coursing through the pipes, the steam will condense and create a vacuum; the water in the pipes will react violently as it is pulled into the vacuum which is what you hear.
It can be a daunting task to find where those troublesome pipes are.
8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

Two btu per sq ft for degree difference for a slab
• Member Posts: 3
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So is this anything I can do?
• Member Posts: 4,106
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Find out who services your steam system and ask them if anything can be done. No one knows your system better than the people who have worked on it.
8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

Two btu per sq ft for degree difference for a slab
• Member Posts: 229
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I'm only just learning about my own steam heating...so my experience is limited....If the banging is in the floor, it could be a poorly pitched pipe that's holding water - then you'd probably need to open the floor to access and fix the section that's banging, right? If the bangin is in the radiator, then (for some types of systems) you can confirm the valve is open all the way and it's pitched right to optimize draining the condensate, right?
New owner of a 1920s home with steam heat north of Boston.
Just trying to learn what I can do myself and what I just shouldn't touch
• Member Posts: 11,109
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This sounds like a one pipe baseboard heater.
The vent end needs to be higher than the valve end.
If the pipe under the floor has sagged you might regain slope on it by raising the valve end of the heater and also raising the vent end an equal amount.
If that pipe will pull up at the valve then the horizonal pipe will raise to drain back. May not take much.
• Member Posts: 2,084
edited March 2019
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Is this a new problem? If so, a pipe hanger may have failed, broke etc. This will/ could cause condensate to pool in the pipe. When steam and condensate meet in the pipe , the noise that you are describing happens. Look to get the pipe properly secured and pitched. This should help get rid of the noise.
• Member Posts: 1,430
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Baseboard and 1-pipe steam won’t ever play nice together...see if the building has any original free standing radiators in the basement they would be willing to put back.